Geology Reference
In-Depth Information
Figure 4.44 Exhumed inclinometer tubing. Four grooves inside (ridges outside) are guides for
the wheels on the inclinometer instrument. The device with arms is a spider, which becomes
fixed in position against the walls of a borehole whilst the tube can pass up or down inside. It
(as well as inclination).
the anchored point moves towards the mining area. Other instru-
ments used to monitor performance at that site included deep
inclinometers and a Leica total station, whereby numerous targets
on the slope surfaces were surveyed remotely and automatically on
an hourly basis, with the data sent to the site of
ce (Hencher
et al., 1996). An inclinometer is a tubular torpedo (with wheels),
which is lowered down a grooved tube set into a borehole or
built into embankment
ll.
Figure 4.44
shows a section of inclin-
ometer casing with the two sets of orthogonal grooves for the
wheels. The torpedo (
Figure 4.45)
is
first lowered down aligned by
the
first set of grooves, then removed and lowered down the
second set of grooves. The section on the
figure also has magnetic
spiders with magnets, through which the tube can slide and can
therefore be used to monitor vertical settlement where the tube is
installed in
fill. Strain gauges within the torpedo measure tilt,
which is recorded against depth. The orthogonal measurements
can be resolved to give the true direction and amount of
displacement.
4.11.1 General
Site investigation needs to include a review of the potential envir-
onmental hazards as well as the immediate ground conditions.
There may be risk from natural landslides and rockfall threatening
the project, potential for natural subsidence or collapse (say in
